The aim of the study is to determine the feasibility of long-term non-invasive home ventilation in ALS patients using the Stellar 150 IVAPS mode, initiated during a single daytime trial, and to assess the number of respiratory therapist interventions subsequently required as well as several patient-centered outcomes. The study will be conducted among patients with ALS referred to the National Program of Home Ventilatory Assistance (NPHVA) at the Montreal Chest Institute. The province-wide program provides home ventilation services to patients with a variety of neuromuscular and other disorders. Referred patients will be randomized to receive traditional Bilevel ventilation in ST mode (BiST) or iVAPS and will be followed over a period of one year. Respiratory therapist interventions (beyond scheduled visits) and changes in ventilator settings will be based on patient complaints and aimed at optimizing patient comfort and ventilator use. In addition, symptoms questionnaires will be administered regularly, overnight oxymetry and transcutaneous capnography (at 6 and 12 months) will be performed. Compliance data will be assessed regularly from ventilator memory downloads at each of the scheduled respiratory therapist home visits (1 week, 1, 6 and 12 months).